①聚苯乙烯　②聚氯乙烯　③聚甲基丙烯酸甲酯　④聚丁二酸乙二酯　⑤酚醛树脂　⑥聚己二酸乙二胺　⑦纤维素醋酸酯　⑧聚丁二酸酐

A.①②③⑤                                   B.③④⑤⑥⑦

C.②③④⑦⑧                                D.④⑥⑦⑧